Toggle Main Menu Toggle Search

Open Access padlockePrints

Effects of different potassium fertilizers suitable for use in organic farming systems on grass/clover yields and nutrient offtakes and interactions with nitrogen supply

Lookup NU author(s): Dr Elizabeth Stockdale


Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


In organic farming systems, fertilizing materials can be used when potassium (K) deficiency is shown, but such systems are dominantly nitrogen (N) limited and this is likely to affect crop utilization of K. The supply of K to grass/clover from a range of mineral and organically based K fertilizers and its interaction with N supply were studied in a greenhouse experiment. Sequential plant cuts were taken for yield and nutrient content determinations in crop and soil. Crop yields were limited by N: where N supply was increased either through the mineralization of N from organic materials (rapemeal, farmyard manure) or inorganic fertilizer, plant yields increased significantly. Grass/clover responded better to additional K where sufficient N was available. However, yield responses to K were generally small, even in the presence of adequate N. Of the different fertilizers, kali and MSL-K increased yields above those of the control by less than 5%, sylvinite, DKSI and farmyard manure by 10-20%, and rapemeal and potassium sulphate by more than 25%. In all treatments, K offtakes in the grass/clover were considerably greater than fertilizer K inputs. The grass/clover showed an increased uptake of Na where insufficient K was available. However, the Mg content of the grass/clover was not adversely affected by K fertilizer application. Organic farmers need to consider the soil K status, the rotational nutrient budget, the supply of all nutrients in fertilizing materials and nutrient interactions to achieve effective K management in organic farming systems.

Publication metadata

Author(s): Fortune S, Hollies J, Stockdale EA

Publication type: Article

Publication status: Published

Journal: Soil Use and Management

Year: 2004

Volume: 20

Issue: 4

Pages: 403-409

Print publication date: 01/12/2004

ISSN (print): 0266-0032

ISSN (electronic): 1475-2743

Publisher: Wiley-Blackwell


DOI: 10.1111/j.1475-2743.2004.tb00389.x


Altmetrics provided by Altmetric